Method for producing a toothbrush handle having an inner cavity

Abstract

Methods of producing toothbrush handles having an inner cavity are provided.

What is claimed is: 
     
       1. A toothbrush handle produced by a method comprising:
 a) providing an extrusion blow mold having a longitudinal axis and a cavity, the cavity having a surface that defines a cross-sectional area wherein the cavity has at least one of a maximum cross-sectional area, bordered by two smaller cross-sectional areas along the longitudinal axis of the blow mold or a minimum cross sectional area bordered by two greater cross-sectional areas along the longitudinal axis of the blow mold; 
 b) extruding a parison comprising a thermoplastic material, the parison includes an interior cavity and an outer surface, wherein the outer surface defines a cross-sectional area of the parison; 
 c) expanding the parison using a fluid to contact the cavity surface and produce a toothbrush handle having an inner cavity; and 
 the toothbrush handle comprising: 
 d) a terminal end, connector end, outer surface, inner cavity, and longitudinal axis; 
 e) the inner cavity having a surface defining a cross-sectional area; wherein the inner cavity has at least one of a greater cross-sectional area, bordered by two lesser cross-sectional areas along the longitudinal axis of the toothbrush or a lesser cross sectional area bordered by two greater cross-sectional areas along the longitudinal axis of the toothbrush; 
 f) the outer surface defining an outer surface cross-sectional area; 
 g) a wall formed from the outer surface and inner cavity surface having a thickness; 
 h) the toothbrush handle comprising a single unitary component; and 
 wherein the toothbrush handle has a specific gravity below about 0.60 g/cm 3  and wherein the toothbrush handle deforms less than about 10 mm under a 5.0N force applied as determined by ASTM D 790. 
 
     
     
       2. The toothbrush handle of  claim 1 , wherein a square root of the outer surface cross-sectional area varies proportionally to a square root of the inner cavity cross-sectional area along the longitudinal axis of the toothbrush. 
     
     
       3. The toothbrush handle of  claim 2 , wherein a square root of the inner cavity surface cross-sectional area varies proportionally less than 5% to the variations in a square root of the outer surface cross-sectional area along the longitudinal axis of the toothbrush handle. 
     
     
       4. The toothbrush handle of  claim 1 , wherein the thickness of the toothbrush handle wall varies in inverse proportion to a square root of the outer surface cross-sectional area. 
     
     
       5. A toothbrush handle produced by a method comprising:
 a) providing an extrusion blow mold having a longitudinal axis and a cavity, the cavity having a surface that defines a cross-sectional area; wherein the cavity has at least one of a maximum cross-sectional area, bordered by two smaller cross-sectional areas along the longitudinal axis of the blow mold or a minimum cross sectional area bordered by two greater cross-sectional areas along the longitudinal axis of the blow mold; 
 b) extruding a parison comprising a first thermoplastic material and a second thermoplastic material, the parison includes an interior cavity and an outer surface, wherein the outer surface defines a cross-sectional area of the parison; 
 c) expanding the parison using a fluid to contact the cavity surface and produce a toothbrush handle having an inner cavity; and 
 the toothbrush handle comprising: 
 d) a terminal end, connector end, outer surface, inner cavity, and longitudinal axis; 
 e) the inner cavity having a surface defining a cross-sectional area; wherein the inner cavity has at least one of a greater cross-sectional area, bordered by two lesser cross-sectional areas along the longitudinal axis of the toothbrush or a lesser cross sectional area bordered by two greater cross-sectional areas along the longitudinal axis of the toothbrush; 
 f) the outer surface defining an outer surface cross-sectional area; 
 g) a wall formed from the outer surface and inner cavity surface; 
 h) the toothbrush handle comprising a single unitary component; and 
 wherein the toothbrush handle has a specific gravity below about 0.60 g/cm 3  and 
 wherein the toothbrush handle deforms less than about 10 mm under a 5.0N force applied as determined by ASTM D 790. 
 
     
     
       6. The toothbrush handle of  claim 5 , wherein a square root of the outer surface cross-sectional area varies proportionally to a square root of the inner cavity cross-sectional area along the longitudinal axis of the toothbrush.